Aerial display: White-bellied Sea Eagle

Birders are always fascinated as well as impressed by the acrobatic aerial displays they witness when observing raptors, especially the White-bellied Sea Eagle (Haliaeetus leucogaster) (left). They always wonder exactly what the birds are up to. Are they fighting? Are they indulging in a particular form of courtship ritual? Or are they at play? The answer can be any one of these three.

The series of dramatic images below of a pair of juvenile White-bellied Sea Eagles captured by Chan Yoke Meng in 2005 probably show the birds at play. But we have no way to be sure. Another series of images by Lee Tiah Khee taken at Kranji recently also show a pair of juvenile White-bellied Sea Eagles in aerial display, again probably at play (bottom). In both cases the eagles are in the process of locking talons.

Play and courtship displays involve a pair of birds, sometimes flying to great heights in circles over the nesting areas. The male sometimes dives at the female who may sideslip or turn over to present her talons. At times this ends up in the pair grappling talons and cartwheeling down to earth, only breaking off at the last moment before they hit the ground.

The birds may also get involved in high-speed chases, sometimes again ending in locking talons, to then roll together in fantastic aerial displays.

While such displays may be closely associated with courtship, the actual mating does not occur in the air but on a nest or in a tree.

And not every cartwheel display is courtship behavior. Cartwheeling is also often associated with aggression and defense of territory. Sometimes the bird may grab at a competitor’s talons or even lock talons and plummet to earth in an effort to intimidate the other party.

Input by YC, images of first panel by Chan Yoke Meng, the second panel and the top image by Lee Tiah Khee through the good office of Ashley Ng.